Push notifications error collection

With !734 (merged) some errors came up in Sentry error logging

Lets please try to keep this list updated

• https://sentry.io/share/issue/141a629774fe4ab08a651d2ff75c4c78/ -- Seems to be the issue that has been caused by the missing nginx configuration
• https://sentry.io/share/issue/e50a91bc74de46e9aa080fcf8e4ebbce/
• The button on the notifications settings page is empty:
  
• On mobile phones it shows the wrong time (past time since the message occurs) #841 (closed)
• sometimes, people experienced that push notifications got deactivated and had to activate it again !1442 (merged)
• !1446 (merged) -- Settings.js will be run on every settings page, also the ones that have no controls for push notifications. Fix: Add null checks for push notification controls
• https://sentry.io/share/issue/beee193013ce4d809d86f1f0693f6ffe/ and https://sentry.io/share/issue/96ebc2e7d4454ab980d746ab922faabc/
  could be Firefox in private browsing mode, see https://bugzilla.mozilla.org/show_bug.cgi?id=1383256
• Currently on beta: TypeError: ServiceWorker script at https://beta.foodsharing.de/sw.js for scope https://beta.foodsharing.de/ threw an exception during script evaluation.
• #892 (closed) Push notifications aren't send when a useres is online: Make online timing more correct. Currently someone counts as online having the browser in background (even for a long time)